How to delete photos in iOS when the trash can icon is grayed out

In both cases, you may need to erase the current contents of the iOS Photos library in the steps that follow, so you should make sure you have a complete backup of all the multimedia you want to save. If you’re already syncing photos with iTunes on a Mac or PC and you’re sure you’re up to date, that’s likely what’s preventing you from deleting images in iOS—I’ll get to that in a moment.

If you’re not already using iTunes, the best advice I can find and offer is to use iPhoto, Photos, or Image Capture to retrieve all the images from your device, even if you only need to do that temporarily. After being sure your photos are completely backed up, then:

1. Connect your iOS device via USB to iTunes on a Mac or PC.
2. Authorize the device if prompted.
3. Select the device in iTunes, and then click the Photos item in the Settings navigation bar.
4. Check the Sync Photos from the box and click Apply at lower right. (If Sync Photos is already checked, see below.)
5. You’ll be prompted to replace the library on your mobile device. Agree, but recognize this wipes out all the photos in iOS.

This will clear whatever state was stuck related to the iOS device. If you don’t want to continue using iTunes for syncing photos, uncheck Sync Photos, click Apply, and the iOS device should be free of that unwanted burden.

If you’ve synced with iTunes in the past, follow steps 1 and 2 above, but in step 3 you should see a checkmark next to Sync Photos. If not, check it and click Apply. Some iOS users report that this seems to update sync status without prompting a warning—that is, their device was previous syncing via iTunes, but not reporting it correctly, and checking the box doesn’t warn them that the library will be wiped from iOS.

You can now uncheck albums and other kinds of photo items in iTunes and click Apply to delete those items; or uncheck Sync Photos, click Apply, and liberate iOS. (Apple has more detailed instructions on general use of this feature.)